This invention relates to a self-service food display for the presentation of food items, for example, a salad bar.
Self-service food displays that present food items to diners need to maintain the food items at an appropriate serving temperature. Thus, the self-service display needs to maintain a cool environment for the case of salad items or other items that need refrigeration. One type of prior art self-service food display provides a cool environment by disposing the food items in containers on a layer of ice. This has the disadvantages of too much cooling, i.e., freezing, and of disposal of melted water.
Another type of refrigerated display counter is shown in U.S. Pat. No. 4,592,209. This display counter has a tray upon which the food is displayed. A cooling air stream is circulated over the food in a direction generally parallel to the tray via a ductwork that extends along the front, under and back sides of the tray. A glass window is provided at the customer or front side of the display case. This display counter has the disadvantage that the diner must lift the glass window to pick up a food item. Also, the display counter is subject to non-uniform temperatures across the length of the salad bar due to heat transfer leakage.
Refrigerated food display cases for food shopping applications typically have a tank in which the food is disposed. A food shopper must reach down into the tank to get a food item. A cooled air stream is circulated over the top of the tank and through a ductwork that extends along the front, under and back sides of the tank. A blower mechanism and a refrigerated evaporator are usually disposed in the ductwork. Refrigerated food display cases of this type are disclosed in U.S. Pat. Nos. 2,967,404, 3,543,532, 4,106,305, 4,295,340 and 4,329, 852.
Thus, there is a need for a self-service display that maintains a uniform temperature for the displayed food items.
There is also a need for a method of maintaining a uniform temperature for the displayed food items.
A self-service food display according to the present invention includes food tray that is supported by a support structure. A ductwork is positioned with respect to the food tray to provide a cooling air stream over and under the food tray. The ductwork includes a plurality of ports arranged to distribute first volumes of the cooling air stream over and under one or more intermediate sections of the food tray to maintain a substantially uniform temperature thereof. The arrangement of ports is also such as to distribute second volumes of the cooling air stream over and under opposed end sections of the food tray. Each of the second volumes is larger than any of the first volumes so as to minimize heat transfer to ambient.
According to another aspect of the self-service food display of the invention, the first and second volumes of the cooling air stream flow are substantially parallel to the food tray. The ports are further positioned to distribute third volumes and fourth volumes of the cooling air stream at an angle to an upper surface of the intermediate and opposed end sections. Each of said fourth volumes is larger than any of said third volumes so as to minimize heat transfer to ambient.
According to another aspect of the self-service food display of the invention, the plurality of ports is further positioned to distribute the cooling air stream in the form of air curtains extending above three sides of the food tray.
An alternate embodiment of the self-service food display of the present invention includes a support structure having a base, a back and a top. A food tray having a front end, a back end and opposed side ends is supported by the support structure so as to be exposed to ambient on the front end and the opposed side ends. A ductwork extends beneath the food tray, up the back and across the top of the support structure. A plurality of air curtain ports is arranged in the ductwork for the formation of a front air curtain and one or more opposed side air curtains. At least one of the air curtain ports is disposed along a front of the top. At least a second one of the air curtain ports is disposed along one of opposed sides of the top. At least a third one of the air curtain ports is disposed along the front end and the opposed side ends of the tray.
According to another aspect of the alternate embodiment, the ductwork is in fluid communication with a passageway directly under the tray so as to provide a first airflow path for the cool air stream to cool the underside of the tray. According to still another aspect of the alternate embodiment, a plurality of ports is disposed in fluid communication with the ductwork in a location to provide a second airflow path substantially parallel to and across an upper surface of the tray.
According to a further aspect of the alternate embodiment, an array of ports is disposed at a location in the ductwork to provide a uniform distribution of air flow in a third path that is incident to an upper surface of the food tray at an acute angle to provide a uniform temperature throughout the third path in the vicinity of the tray.
According to a still further aspect of the alternate embodiment, the food tray has two opposed side sections and one or more intermediate sections. A first volume of the cool air stream is uniformly distributed under the intermediate sections and larger volumes of the cool air stream are distributed under any of the opposed sections that are exposed to ambient to minimize heat transfer.
The method of the present invention cools a food tray of a self-service food display. The food tray has a pair of opposed end sections and one or more intermediate sections. The method provides a cooling air stream. The cooling air stream is flowed over and under the intermediate sections in a manner to provide a substantially uniform temperature in the vicinity of the food tray. The cooling air stream is also flowed over and under the opposed end sections in a manner to minimize heat transfer to ambient.
According to an aspect of the method of the invention, also flows the cooling air stream in a manner to provide an air curtain that extends above three sides of the food tray. According to another aspect of the method, the cooling air stream is also flowed at an acute angle to an upper surface of the food tray in a manner that provides uniform volumes of the cooling air stream to the intermediate sections. This flow also provides higher volumes of the cooling air stream to the opposed end sections to minimize heat transfer to ambient.